Opening/closing body drive device and control method thereof

ABSTRACT

An opening/closing body drive device includes: a motor which opens or closes an opening/closing body; a drive unit which rotates the motor; and a control unit which controls the drive unit. The drive unit includes first and second integrated circuits having first and second switching elements and third and fourth switching elements which are connected to each other in series with respect to a power source and connection points of which are connected to one and the other terminals of the motor, respectively. The control unit turn-on drives only the second switching element when braking the motor during the forward rotation and turn-on drives only the fourth switching element when braking the motor during the reverse rotation, or turn-on drives only the third switching element when braking the motor during the forward rotation and turn-on drives only the first switching element when braking the motor during the reverse rotation.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. § 119to Japanese Patent Application 2019-176980, filed on Sep. 27, 2019, theentire content of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to an opening/closing body drive device and acontrol method thereof.

BACKGROUND DISCUSSION

In the related art, an opening/closing body drive device is known, whichincludes a motor for opening or closing a toilet seat, a drive unit forsupplying electric power from a power source to the motor to rotate themotor forward or reversely, and a microcomputer for controlling thedrive unit (for example, refer to JP 2018-201646A). Here, the drive unitincludes an H bridge circuit having first to fourth switching elements.A set of the first and second switching elements connected in series anda set of the third and fourth switching elements connected in series areconnected in parallel to each other, and a connection point of the firstand second switching elements and a connection point of the third andfourth switching elements are connected to both terminals of the motor.Moreover, a voltage from the power source is applied to a connectionpoint of the first and third switching elements, and a connection pointof the second and fourth switching elements is grounded. In thisopening/closing body drive device, the motor can be driven to be rotatedforward by turning on (applying power to) the first and fourth switchingelements. Further, the motor can be driven to be rotated reversely byturning on the second and third switching elements. Further, it ispossible to short-circuit both terminals of the motor and apply a brake(short brake) to a rotation of the motor by turn-on driving the secondand fourth switching elements.

A first integrated circuit having first and second switching elementsand a second integrated circuit having third and fourth switchingelements may be used as a drive unit. In this case, when the motor isbraked by turn-on driving the second and fourth switching elementsduring a forward rotation or a reverse rotation of the motor, thermalloads of the first and second integrated circuits caused by switchinglosses of the second and fourth switching elements may reduce life ofthe first and second integrated circuits.

A need thus exists for an opening/closing body drive device and acontrol method thereof which are not susceptible to the drawbackmentioned above.

SUMMARY

An opening/closing body drive device and the control method thereofaccording to this disclosure adopts the following means.

An opening/closing body drive device according to an aspect of thisdisclosure includes: a motor which opens or closes an opening/closingbody; a drive unit which rotates the motor; and a control unit whichcontrols the drive unit, in which the drive unit includes a firstintegrated circuit having first and second switching elements which areconnected to each other in series with respect to a positive electrodeside and a negative electrode side of a power source and a connectionpoint of which is connected to one terminal of the motor, and a secondintegrated circuit having third and fourth switching elements which areconnected to each other in series with respect to the positive electrodeside and the negative electrode side and a connection point of which isconnected to the other terminal of the motor, first to fourthfreewheeling diodes are incorporated in or attached in parallel to thefirst to fourth switching elements, the control unit turn-on drives thefirst and fourth switching elements when driving the motor to be rotatedforward and turn-on drives the second and third switching elements whendriving the motor to be rotated reversely, and the control unit turn-ondrives only the second switching element of the first to fourthswitching elements when braking the motor during the forward rotation ofthe motor and turn-on drives only the fourth switching element of thefirst to fourth switching elements when braking the motor during thereverse rotation of the motor, or the control unit turn-on drives onlythe third switching element of the first to fourth switching elementswhen braking the motor during the forward rotation of the motor andturn-on drives only the first switching element of the first to fourthswitching elements when braking the motor during the reverse rotation ofthe motor.

A control method of opening/closing body drive device according toanother aspect of this disclosure is a control method of opening/closingbody drive device including: a motor which opens or closes anopening/closing body, and a drive unit which rotates the motor, in whichthe drive unit includes a first integrated circuit having first andsecond switching elements which are connected to each other in serieswith respect to a positive electrode side and a negative electrode sideof a power source and a connection point of which is connected to oneterminal of the motor, and a second integrated circuit having third andfourth switching elements which are connected to each other in serieswith respect to the positive electrode side and the negative electrodeside and a connection point of which is connected to the other terminalof the motor, and first to fourth freewheeling diodes are incorporatedin or attached in parallel to the first to fourth switching elements.The method includes: turn-on driving the first and fourth switchingelements when driving the motor to be rotated forward and turn-ondriving the second and third switching elements when driving the motorto be rotated reversely; and turn-on driving only the second switchingelement of the first to fourth switching elements when braking the motorduring the forward rotation of the motor and turn-on driving only thefourth switching element of the first to fourth switching elements whenbraking the motor during the reverse rotation of the motor, or turn-ondriving only the third switching element of the first to fourthswitching elements when braking the motor during the forward rotation ofthe motor and turn-on driving only the first switching element of thefirst to fourth switching elements when braking the motor during thereverse rotation of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of thisdisclosure will become more apparent from the following detaileddescription considered with the reference to the accompanying drawings,wherein:

FIG. 1 is an external view of a vehicle including a back door drivedevice as an opening/closing body drive device of the presentembodiment;

FIG. 2 is a configuration diagram illustrating an outline of aconfiguration of the back door drive device;

FIG. 3 is a flowchart illustrating an example of a processing routineexecuted by a microcomputer; and

FIG. 4 is a configuration diagram illustrating an outline of aconfiguration of the back door drive device.

DETAILED DESCRIPTION

Next, embodiments of this disclosure will be described with reference tothe drawings.

FIG. 1 is an external view of a vehicle 10 including a back door drivedevice 20 as an opening/closing body drive device of the presentembodiment. FIG. 2 is a configuration diagram illustrating an outline ofa configuration of the back door drive device 20. As illustrated in thedrawings, the vehicle 10 of the present embodiment includes a flip-uptype back door BD which is supported by a vehicle body 12 via hinges 13so as to be openable and closable, extendable support members 14, a doorcloser 16, and the back door drive device 20 for opening and closing theback door BD. The door closer 16 is incorporated in a lower innerportion of the back door BD so as to be engageable with the striker 17fixed to a lower portion of an opening portion of the vehicle body 12opened and closed by the back door BD.

The back door drive device 20 is configured as a device which opens orcloses the back door BD by converting a rotation of the motor 22 into alinear motion and expanding and contracting the support member 14. Theback door drive device 20 includes a motor 22 which opens or closes theback door BD, a drive unit 30 which rotates the motor 22, and amicrocomputer (control unit) 40 which controls the drive unit 30. In theembodiment, rotation directions of the motor 22 for closing and openingthe back door BD are referred to as a forward direction and a reversedirection of the motor 22, respectively.

The drive unit 30 includes integrated circuits 31 and 35. The integratedcircuit 31 is configured as a half bridge IC having switching elementsS1 and S2 connected to each other in series, and the integrated circuit35 is configured as a half bridge IC having switching elements S3 and S4connected to each other in series. As the switching elements S1 and S3,p-channel field effect transistors (FETs) in which parasitic diodes(body diodes) D1 and D3 functioning as freewheeling diodes areincorporated are used, respectively. Further, as the switching elementsS2 and S4, n-channel field effect transistors (FETs) in which parasiticdiodes D2 and D4 functioning as freewheeling diodes are incorporated areused, respectively.

A set of the switching elements S1 and S2 and a set of the switchingelements S3 and S4 are connected to each other in parallel. One terminalof the motor 22 is connected to a connection point P1 of the switchingelements S1 and S2, and the other terminal of the motor 22 is connectedto a connection point P2 of the switching elements S3 and S4. Aconnection point Pv of the switching elements S1 and S3 is connected toa positive electrode side of a power source via a power line, and aconnection point Pg of the switching elements S2 and S4 is grounded(connected to a negative electrode side of the power source via a powerline such as a metal case). In this way, the switching elements S1 to S4form an H bridge circuit.

The integrated circuit 31 includes, in addition to the switchingelements S1 and S2, overcurrent detection units 32 a and 32 b fordetecting overcurrent of the switching elements S1 and S2, a processingunit 33, and a communication port (port for INH1 signal or port for IN1signal). The processing unit 33 turn-on drives the switching elements S1and S2 based on the INH1 signal or the IN1 signal from the microcomputer40. Specifically, the processing unit 33 turns off (does not turn-ondrive) both the switching elements S1 and S2 when the INH1 signal isoff, the processing unit 33 turn-on drives the switching element S1 whenboth the INH1 signal and the IN1 signal are on, and the processing unit33 turn-on drives the switching element S2 when the INH1 signal is onand the IN1 signal is off. Here, the “turn-on drive” includes drivewhich is held to be turned on and drive which is turned on or off by apulse width modulation (PWM) control. The processing unit 33 has a firstprotection function of, when an overcurrent of the switching element S1is detected during turn-on driving of the switching element S1,switching the turning-on driving of the switching element S1 to theturn-on driving of the switching element S2 regardless of the IN1signal, and when an overcurrent of the switching element S2 is detectedduring turn-on driving of the switching element S2, switching theturning-on driving of the switching element S2 to the turn-on driving ofthe switching element S1 regardless of the IN1 signal.

The integrated circuit 35 includes, in addition to the switchingelements S3 and S4, overcurrent detection units 36 a and 36 b fordetecting overcurrent of the switching elements S3 and S4, a processingunit 37, and a communication port (port for INH2 signal or port for IN2signal). The processing unit 37 turn-on drives the switching elements S3and S4 based on the INH2 signal or the IN2 signal from the microcomputer40. Specifically, the processing unit 37 turns off both the switchingelements S3 and S4 when the INH2 signal is off, the processing unit 37turn-on drives the switching element S3 when both the INH2 signal andthe IN2 signal are on, and the processing unit 37 turn-on drives theswitching element S4 when the INH2 signal is on and the IN2 signal isoff. The processing unit 37 has a second protection function of, when anovercurrent of the switching element S3 is detected during turn-ondriving of the switching element S3, switching the turning-on driving ofthe switching element S3 to the turn-on driving of the switching elementS4 regardless of the IN2 signal, and when an overcurrent of theswitching element S4 is detected during turn-on driving of the switchingelement S4, switching the turning-on driving of the switching element S4to the turn-on driving of the switching element S3 regardless of the IN2signal.

The microcomputer 40 is configured as a microcomputer having a CPU, ROM,RAM, and an input/output port. A rotation speed Nm of the motor 22 froma rotation speed sensor 23 which detects the rotation speed of the motor22 is input to the microcomputer 40 via an input port. The microcomputer40 outputs the INH1 signal and the IN1 signal to the integrated circuit31 and the INH2 signal and the IN2 signal to the integrated circuit 35through the output port.

In the back door drive device 20 of the embodiment configured asdescribed above, when the motor 22 is driven to be rotated forward inresponse to a switch operation (switch is not illustrated) or the likefor closing the back door BD by the user and the back door BD is closed,the microcomputer 40 controls the INH1 signal, the IN1 signal, the INH2signal, and the IN2 signal so that the switching elements S1 and S4 areturn-on driven. Further, when the motor 22 is driven to be rotatedreversely in response to a switch operation or the like for opening theback door BD by the user and the back door BD is opened, themicrocomputer 40 controls the INH1 signal, the IN1 signal, the INH2signal, and the IN2 signal so that the switching elements S2 and S3 areturn-on driven. The motor 22 rotates forward or reversely even when theback door BD moves in a closing direction or an opening direction by anoperation of the back door BD in the closing direction or the openingdirection by the user or weight of the back door BD.

Next, an operation of the back door drive device 20 of the embodimentconfigured as described above, particularly an operation when brakingthe motor 22 will be described. FIG. 3 is a flowchart illustrating anexample of a processing routine executed by the microcomputer 40. Thisroutine is executed when the motor 22 starts rotating (forward rotationor reverse rotation).

When the processing routine of FIG. 3 is executed, first, themicrocomputer 40 determines whether or not a braking condition issatisfied (Step S100), and when the microcomputer 40 determines that thebraking condition is not satisfied, the microcomputer 40 waits for thebraking conditions to be satisfied. Here, as the braking condition, acondition in which an absolute value of the rotation speed Nm of themotor 22 is a threshold value Nmref or more, a condition in which aposition of the back door BD is located between a predetermined positionslightly before (on a slightly open side or a slightly closed side of) atarget stop position (fully closed position or fully open position) anda target stop position, or the like is used. The threshold value Nmrefis used to determine whether or not the absolute value of the rotationspeed Nm of the motor 22 is relatively large. The position of the backdoor BD is estimated based on a length (an amount of expansion andcontraction) of the support member 14 detected by a sensor (notillustrated). The predetermined position is determined so that the backdoor BD can be stopped at the target stop position by braking the motor22. In the embodiment, it is determined that the braking condition issatisfied when at least one of these conditions is satisfied.

When it is determined in Step S100 that the braking condition issatisfied, it is determined whether or not it is immediately after startof the satisfaction of the braking condition (Step S110). When it isdetermined that it is immediately after the start of the satisfaction ofthe braking condition, the INH1 signal, IN1 signal, INH2 signal, and IN2signal are controlled so that all of the switching elements S1 to S4 areturned off (Step S120). As a result, when the motor 22 is driven to berotated forward or reversely, the driving is stopped. When it isdetermined in Step S110 that it is not immediately after the start ofthe satisfaction of the braking condition (satisfaction of the brakingcondition is continuously performed), the processing of Step S120 is notexecuted.

Subsequently, the rotation direction (movement direction of the backdoor BD) of the motor 22 is determined based on the rotation speed Nm ofthe motor 22 (Step S130). When the user performs a switch operation foropening or closing the back door BD, the rotation direction of the motor22 may be determined based on the switch operation.

When it is determined in Step S130 that the motor 22 rotates forward(the back door BD is closed), the INH1 signal, the IN1 signal, the INH2signal, and the IN2 signal are controlled so that only the switchingelement S2 among the switching elements S1 to S4 is turn-on driven (StepS140). When the motor 22 is rotated forward, if only the switchingelement S2 among the switching elements S1 to S4 is turn-on driven, aclosed circuit of the switching element S2, the parasitic diode D4, themotor 22, and the switching element S2 is formed, and thus, it ispossible to brake the motor 22.

When it is determined in Step S130 that the motor 22 rotates reversely(the back door BD is opened), the INH1 signal, the IN1 signal, the INH2signal, and the IN2 signal are controlled so that only the switchingelement S4 among the switching elements S1 to S4 is turn-on driven (StepS150). When the motor 22 is rotated reversely, if only the switchingelement S4 among the switching elements S1 to S4 is turn-on driven, aclosed circuit of the switching element S4, the parasitic diode D2, themotor 22, and the switching element S4 is formed, and thus, it ispossible to brake the motor 22.

Then, it is determined whether or not the rotation of the motor 22 isstopped (Step S160), and when it is determined that the motor 22rotates, the processing returns to Step S100. In this way, theprocessing of Steps S100 to S160 is repeatedly executed, and when it isdetermined in Step S160 that the rotation of the motor 22 is stopped,this routine ends.

Here, as a comparative mode, a mode in which the motor 22 is braked byturn-on driving the switching elements S2 and S4 of the integratedcircuits 31 and 35 regardless of the rotation direction of the motor 22is considered. In this comparative mode, thermal loads of the integratedcircuits 31 and 35 caused by switching losses of the switching elementsS2, and S4 or the like may reduce life of the integrated circuits 31 and35. Meanwhile, in the present embodiment, the switching element S2 ofthe integrated circuit 31 is turn-on driven when braking the motor 22during the forward rotation of the motor 22, and the switching elementS4 of the integrated circuit 35 is turn-on driven when braking the motor22 during the reverse rotation of the motor 22. That is, the switchingelements of different integrated circuits are turn-on driven whenbraking the motor 22 during the forward rotation of the motor 22 andwhen braking the motor 22 during the reverse rotation of the motor 22.Accordingly, it is possible to reduce accumulation of thermal loadsacting on the integrated circuits 31 and 35. As a result, it is possibleto suppress a decrease in the life of the integrated circuits 31 and 35.

Further, in the comparative mode, the following inconvenience may occur.When an overcurrent flows to the switching element S2 and the firstprotection function of the integrated circuit 31 is operated, the motor22 is driven to be rotated forward by the turn-on driving of theswitching elements S1 and S4. When an overcurrent flows to the switchingelement S4 and the second protection function of the integrated circuit35 is operated, the motor 22 is driven to be rotated reversely by theturn-on driving of the switching elements S2 and S3. Meanwhile, only theswitching element S2 is turn-on driven, and thus, even if theovercurrent flows to the switching element S2 and the first protectionfunction of the integrated circuit 31 is operated to turn-on drive theswitching element S1, the motor 22 is not driven. Further, only theswitching element S4 is turn-on driven, and thus, even if theovercurrent flows to the switching element S4 and the second protectionfunction of the integrated circuit 35 is operated to turn-on drive theswitching element S3, the motor 22 is not driven. As a result, it ispossible to prevent the motor 22 from being driven when the braking isrequired for the motor 22.

In the back door drive device 20 of the present embodiment describedabove, when the braking condition is satisfied during the forwardrotation of the motor 22, only the switching element S2 is turn-ondriven, and when the braking condition is satisfied during the reverserotation of the motor 22, only the switching element S4 is turn-ondriven. Therefore, the switching elements of different integratedcircuits are turn-on driven when the motor 22 is braked during theforward rotation of the motor 22 and when the motor 22 is braked duringthe reverse rotation of the motor 22, and thus, it is possible to reducethe accumulation of the thermal loads acting on the integrated circuits31 and 35. As a result, it is possible to suppress a decrease in thelife of the integrated circuits 31 and 35.

In the embodiment, when the braking condition is satisfied during theforward rotation of the motor 22, only the switching element S2 of theintegrated circuit 31 is turn-on driven, and when the braking conditionis satisfied during the reverse rotation of the motor 22, only theswitching element S4 of the integrated circuit 35 is turn-on driven.However, when the braking condition is satisfied during the forwardrotation of the motor 22, only the switching element S3 of theintegrated circuit 35 may be turn-on driven, and when the brakingcondition is satisfied during the reverse rotation of the motor 22, onlythe switching element S1 of the integrated circuit 31 may be turn-ondriven. Even in this case, it is possible to suppress the decrease inthe life of the integrated circuits 31 and 35.

In the embodiment, the integrated circuits 31 and 35 have the first andsecond protection functions, respectively, but may not have the firstand second protection functions.

In the embodiment, as illustrated in the back door drive device 20 ofFIG. 2, the p-channel field effect transistors in which the parasiticdiodes D1 and D3 functioning as the freewheeling diodes are incorporatedare used as the switching elements S1 and S3, and the n-channel fieldeffect transistors in which the parasitic diodes D2 and D4 functioningas the freewheeling diodes are incorporated are used as the switchingelements S2 and S4. However, as illustrated in a back door drive device20B of FIG. 4, for example, insulated gate bipolar transistors (IGBTs)S11 to S14 may be used as switching elements S11 to S14, andfreewheeling diodes D11 to D14 may be attached in reversely parallel tothe switching elements S11 to S14. The back door drive device 20B is thesame as the back door drive device 20 except that the switching elementsS1 to S4 in which the parasitic diodes D1 to D4 are incorporated arereplaced with the switching elements S11 to S14 and the freewheelingdiodes D11 to D14.

In the embodiment, the back door drive device 20 which opens or closesthe back door BD is described as the opening/closing body drive device,but this disclosure is not limited to this. That is, the opening/closingbody drive device may be a drive device which opens or closes a slidedoor of a vehicle or the like.

In the embodiment, this disclosure is described as the form of theopening/closing body drive device, but may be described in a form of acontrol method of the opening/closing body drive device.

A correspondence between main elements of the embodiment and the mainelements of this disclosure described in Summary will be described. Inthe embodiment, the motor 22 corresponds to a “motor”, the drive unit 30corresponds to a “drive unit”, and the microcomputer 40 corresponds to a“control unit”.

A correspondence between the main elements of the embodiment and themain elements of this disclosure described in Summary is an example ofan embodiment for specifically explaining a mode for carrying out thisdisclosure described in Summary, and thus, does not limit the elementsof this disclosure described in Summary. That is, an interpretation ofthis disclosure described in Summary should be made based on thedescription in Summary, and the embodiments are a merely specificexample of this disclosure described in Summary.

Hereinbefore, the embodiments for carrying out this disclosure aredescribed. However, this disclosure is not limited to the embodiments,and various embodiments can be carried out within a scope which does notdepart from a gist of this disclosure.

This disclosure can be used in a manufacturing industry of theopening/closing body drive device.

An opening/closing body drive device according to an aspect of thisdisclosure includes: a motor which opens or closes an opening/closingbody; a drive unit which rotates the motor; and a control unit whichcontrols the drive unit, in which the drive unit includes a firstintegrated circuit having first and second switching elements which areconnected to each other in series with respect to a positive electrodeside and a negative electrode side of a power source and a connectionpoint of which is connected to one terminal of the motor, and a secondintegrated circuit having third and fourth switching elements which areconnected to each other in series with respect to the positive electrodeside and the negative electrode side and a connection point of which isconnected to the other terminal of the motor, first to fourthfreewheeling diodes are incorporated in or attached in parallel to thefirst to fourth switching elements, the control unit turn-on drives thefirst and fourth switching elements when driving the motor to be rotatedforward and turn-on drives the second and third switching elements whendriving the motor to be rotated reversely, and the control unit turn-ondrives only the second switching element of the first to fourthswitching elements when braking the motor during the forward rotation ofthe motor and turn-on drives only the fourth switching element of thefirst to fourth switching elements when braking the motor during thereverse rotation of the motor, or the control unit turn-on drives onlythe third switching element of the first to fourth switching elementswhen braking the motor during the forward rotation of the motor andturn-on drives only the first switching element of the first to fourthswitching elements when braking the motor during the reverse rotation ofthe motor.

In the opening/closing body drive device according to the aspect of thisdisclosure, only the second switching element of the first to fourthswitching elements is turn-on driven when braking the motor during theforward rotation of the motor and only the fourth switching element ofthe first to fourth switching elements is turn-on driven when brakingthe motor during the reverse rotation of the motor, or only the thirdswitching element of the first to fourth switching elements is turn-ondriven when braking the motor during the forward rotation of the motorand only the first switching element of the first to fourth switchingelements is turn-on driven when braking the motor during the reverserotation of the motor. Therefore, the switching elements of differentintegrated circuits are turn-on driven when the motor is braked duringthe forward rotation of the motor and when the motor is braked duringthe reverse rotation of the motor, and thus, it is possible to reduceaccumulation of a thermal load acting on the first and second integratedcircuits. As a result, it is possible to suppress a decrease in life ofthe first and second integrated circuits. When only the second switchingelement is turn-on driven during the forward rotation of the motor, aclosed circuit of the second switching element, the fourth freewheelingdiode, the motor, and the second switching element is formed, and thus,it is possible to brake the motor. When only the fourth switchingelement is turn-on driven during the reverse rotation of the motor, aclosed circuit of the fourth switching element, the second freewheelingdiode, the motor, and the fourth switching element is formed, and thus,it is possible to brake the motor. When only the third switching elementis turn-on driven during the forward rotation of the motor, a closedcircuit of the third switching element, the motor, the firstfreewheeling diode, and the third switching element is formed, and thus,it is possible to brake the motor. When only the first switching elementis turn-on driven during the reverse rotation of the motor, a closedcircuit of the first switching element, the motor, the thirdfreewheeling diode, and the first switching element is formed, and thus,it is possible to brake the motor.

In the opening/closing body drive device according to the aspect of thisdisclosure, the first integrated circuit may have a first protectionfunction of, when an overcurrent of the first switching element isdetected during the turn-on driving of the first switching element,switching the turn-on driving of the first switching element to theturn-on driving of the second switching element, and when an overcurrentof the second switching element is detected during the turn-on drivingof the second switching element, switching the turn-on driving of thesecond switching element to the turn-on driving of the first switchingelement, and the second integrated circuit may have a second protectionfunction of, when an overcurrent of the third switching element isdetected during the turn-on driving of the third switching element,switching the turn-on driving of the third switching element to theturn-on driving of the fourth switching element, and when an overcurrentof the fourth switching element is detected during the turn-on drivingof the fourth switching element, switching the turn-on driving of thefourth switching element to the turn-on driving of the third switchingelement. In this case, in a case where the second and fourth switchingelements are turn-on driven regardless of the rotation direction of themotor when the motor is braked during the forward rotation or thereverse rotation of the motor, when the first protection function isoperated, the motor is driven to be rotated forward by turn-on drivingthe first and fourth switching elements, or when the second protectionfunction is operated, the motor is driven to be rotated reversely byturn-on driving the second and third switching elements. Meanwhile, byturn-on driving only one of the first to fourth switching elements, itis possible to prevent the motor from being driven when braking isrequested for the motor.

A control method of opening/closing body drive device according toanother aspect of this disclosure is a control method of opening/closingbody drive device including: a motor which opens or closes anopening/closing body, and a drive unit which rotates the motor, in whichthe drive unit includes a first integrated circuit having first andsecond switching elements which are connected to each other in serieswith respect to a positive electrode side and a negative electrode sideof a power source and a connection point of which is connected to oneterminal of the motor, and a second integrated circuit having third andfourth switching elements which are connected to each other in serieswith respect to the positive electrode side and the negative electrodeside and a connection point of which is connected to the other terminalof the motor, and first to fourth freewheeling diodes are incorporatedin or attached in parallel to the first to fourth switching elements.The method includes: turn-on driving the first and fourth switchingelements when driving the motor to be rotated forward and turn-ondriving the second and third switching elements when driving the motorto be rotated reversely; and turn-on driving only the second switchingelement of the first to fourth switching elements when braking the motorduring the forward rotation of the motor and turn-on driving only thefourth switching element of the first to fourth switching elements whenbraking the motor during the reverse rotation of the motor, or turn-ondriving only the third switching element of the first to fourthswitching elements when braking the motor during the forward rotation ofthe motor and turn-on driving only the first switching element of thefirst to fourth switching elements when braking the motor during thereverse rotation of the motor.

In the control method for the opening/closing body drive deviceaccording to the aspect of this disclosure, only the second switchingelement of the first to fourth switching elements is turn-on driven whenbraking the motor during the forward rotation of the motor and only thefourth switching element of the first to fourth switching elements isturn-on driven when braking the motor during the reverse rotation of themotor, or only the third switching element of the first to fourthswitching elements is turn-on driven when braking the motor during theforward rotation of the motor and only the first switching element ofthe first to fourth switching elements is turn-on driven when brakingthe motor during the reverse rotation of the motor. Therefore, theswitching elements of different integrated circuits are turn-on drivenwhen the motor is braked during the forward rotation of the motor andwhen the motor is braked during the reverse rotation of the motor, andthus, it is possible to reduce accumulation of a thermal load acting onthe first and second integrated circuits. As a result, it is possible tosuppress a decrease in life of the first and second integrated circuits.When only the second switching element is turn-on driven during theforward rotation of the motor, a closed circuit of the second switchingelement, the fourth freewheeling diode, the motor, and the secondswitching element is formed, and thus, it is possible to brake themotor. When only the fourth switching element is turn-on driven duringthe reverse rotation of the motor, a closed circuit of the fourthswitching element, the second freewheeling diode, the motor, and thefourth switching element is formed, and thus, it is possible to brakethe motor. When only the third switching element is turn-on drivenduring the forward rotation of the motor, a closed circuit of the thirdswitching element, the motor, the first freewheeling diode, and thethird switching element is formed, and thus, it is possible to brake themotor. When only the first switching element is turn-on driven duringthe reverse rotation of the motor, a closed circuit of the firstswitching element, the motor, the third freewheeling diode, and thefirst switching element is formed, and thus, it is possible to brake themotor.

The principles, preferred embodiment and mode of operation of thepresent invention have been described in the foregoing specification.However, the invention which is intended to be protected is not to beconstrued as limited to the particular embodiments disclosed. Further,the embodiments described herein are to be regarded as illustrativerather than restrictive. Variations and changes may be made by others,and equivalents employed, without departing from the spirit of thepresent invention. Accordingly, it is expressly intended that all suchvariations, changes and equivalents which fall within the spirit andscope of the present invention as defined in the claims, be embracedthereby.

What is claimed is:
 1. An opening/closing body drive device comprising:a motor which opens or closes an opening/closing body; a drive unitwhich rotates the motor; and a control unit which controls the driveunit, wherein the drive unit includes a first integrated circuit havingfirst and second switching elements which are connected to each other inseries with respect to a positive electrode side and a negativeelectrode side of a power source and a connection point of which isconnected to one terminal of the motor, and a second integrated circuithaving third and fourth switching elements which are connected to eachother in series with respect to the positive electrode side and thenegative electrode side and a connection point of which is connected tothe other terminal of the motor, first to fourth freewheeling diodes areincorporated in or attached in parallel to the first to fourth switchingelements, the control unit turn-on drives the first and fourth switchingelements when driving the motor to be rotated forward and turn-on drivesthe second and third switching elements when driving the motor to berotated reversely, and the control unit turn-on drives only the secondswitching element of the first to fourth switching elements when brakingthe motor during the forward rotation of the motor and turn-on drivesonly the fourth switching element of the first to fourth switchingelements when braking the motor during the reverse rotation of themotor, or the control unit turn-on drives only the third switchingelement of the first to fourth switching elements when braking the motorduring the forward rotation of the motor and turn-on drives only thefirst switching element of the first to fourth switching elements whenbraking the motor during the reverse rotation of the motor.
 2. Theopening/closing body drive device according to claim 1, wherein thefirst integrated circuit has a first protection function of, when anovercurrent of the first switching element is detected during theturn-on driving of the first switching element, switching the turn-ondriving of the first switching element to the turn-on driving of thesecond switching element, and when an overcurrent of the secondswitching element is detected during the turn-on driving of the secondswitching element, switching the turn-on driving of the second switchingelement to the turn-on driving of the first switching element, and thesecond integrated circuit has a second protection function of, when anovercurrent of the third switching element is detected during theturn-on driving of the third switching element, switching the turn-ondriving of the third switching element to the turn-on driving of thefourth switching element, and when an overcurrent of the fourthswitching element is detected during the turn-on driving of the fourthswitching element, switching the turn-on driving of the fourth switchingelement to the turn-on driving of the third switching element.
 3. Acontrol method of an opening/closing body drive device including a motorwhich opens or closes an opening/closing body, and a drive unit whichrotates the motor, in which the drive unit includes a first integratedcircuit having first and second switching elements which are connectedto each other in series with respect to a positive electrode side and anegative electrode side of a power source and a connection point ofwhich is connected to one terminal of the motor, and a second integratedcircuit having third and fourth switching elements which are connectedto each other in series with respect to the positive electrode side andthe negative electrode side and a connection point of which is connectedto the other terminal of the motor, and in which first to fourthfreewheeling diodes are incorporated in or attached in parallel to thefirst to fourth switching elements, the method comprising: turn-ondriving the first and fourth switching elements when driving the motorto be rotated forward and turn-on driving the second and third switchingelements when driving the motor to be rotated reversely; and turn-ondriving only the second switching element of the first to fourthswitching elements when braking the motor during the forward rotation ofthe motor and turn-on driving only the fourth switching element of thefirst to fourth switching elements when braking the motor during thereverse rotation of the motor, or turn-on driving only the thirdswitching element of the first to fourth switching elements when brakingthe motor during the forward rotation of the motor and turn-on drivingonly the first switching element of the first to fourth switchingelements when braking the motor during the reverse rotation of themotor.